Self-mating electric connector assembly



Nov. 12, 1968 c. J. ADAMS SELF-MATING ELECTRIC CONNECTOR ASSEMBLY 2Sheets-Sheet 1 Filed July 8, 1963 mvs/vro/e CHARLES J ADAMS, 5y 7",,A1.ze-4

ATTORNEY.

Nov. 12, 1968 c. J. ADAMS 3,411,127

SELF-MATING ELECTRIC CONNECTOR ASSEMBLY Filed July 6, 1963 2Sheets-Sheet 2 A K A /4 2/ 2/ c X I w V m V I W W ld 'a A5 of 7 I I r V'A uvvmvroa: CHARLES JADAMS,

5y 7' ATTORNEY.

United States Patent 3,411,127 SELF-MATING ELECTRIC CONNECTOR ASSEMBLYCharles J. Adams, Bloomington, lll., assignor to General ElectricCompany, a corporation of New York Filed July 8, 1963, Ser. No. 293,4153 Claims. (Cl. 339-47) My invention relates to detachable electricconnector contacts of the self-mating or hermaphrodite type, andparticularly to a multiplanar two-finger contact of this type havingimproved electrical and mechanical engagement. My improved connectorcontact is especially adapted for multiple mounting in large arrays orbanks for quick detachable connection of printed circuit boards or otherelectrical subassemblies.

With the recent rapid development of complex electric informationhandling apparatus, for example telephone dialing equipment, electroniccomputer and detection apparatus, automatic machine tool controlapparatus and the like, there has arisen a need for modular circuitassembly to facilitate eflicient subassembly and rapid replacement ofindividual circuit elements and functional units. The accompanyingdevelopment of printed electrical circuitry and elemental printedcircuit board assemblies has facilitated such modular construction.These developments have created a need for improved detachable electricconnector contacts of small size especially adapted for multipleassembly in large numbers in closely spaced cooperating arrays. Y

A variety of electric contacts have been devised and used in modularsignal circuit assembles of the types referred to. Conveniently, many ofthese have been selfmating or hermaphrodite types wherein each contactis designed to mate with another having the same configuration at itsmating end. While these devices as previously known have performedsatisfactorily to a degree, they have demonstrated certain limitations.For example, many such contacts may be conveniently mated only with oneof identical mating end configuration and not with other commerciallyavailable types having differently configured mating ends; in some themechanical forces required for connection and disconnection of largebanks of contacts is inordinately large; in some the electric contactarea is limited and thus generates excessive heat, and in some themechanical forces developed during mating create such stress in thecontact that deformation and fatigue precludes more than a limitednumber of mating operations.

Accordingly it is a primary object of my invention to provide a noveland improved electric connector contact of the self-mating type havingimproved electrical and mechanical engagement characteristics.

It is another object of my invention to provide a novel and improvedtwo-finger electric contact designed primarily for hermaphrodite matingwith a contact having a mating end of identical configuration butadapted also to mate with a bifurcated contact having a differentlyconfigured mating end.

-It is still another object of my invention to provide a novel andimproved multiplanar two-finger electric contact which provides a largecontacting area when mated with another having the same mating endconfiguration and which will mate also with a bifurcated contact ofuniplanar type.

It is a particular object of my invention to provide a novel andimproved two-finger hermaphrodite contact designed for spring-pressedcontact engagement in fiatwise or broad area planar relation without thedevelopmentof unbalanced rotational forces on the contact mounting.

It is a still further object of my invention to provide a novel andimproved electric contact matable with itself and matable also withconventional contacts, and having unique guide tips to facilitate matingand to limit the degree of mating.

In carrying out my invention in one preferred embodiment, I provide ablade of resilient electric conducting material having one end formed toprovide a mounting base and having at its other end a multiplanar,two-fingered mating contact head. The contact head is formed by slittingthe blade longitudinally to define a single pair of elongated contactfingers disposed in closely spaced edge-to-edge relation and havingopposite planar, broad area contacting faces. The fingers are relativelyoffset in a direction perpendicular to their planar faces by an amountapproximately equal to the blade thickness, so that the fingers residein parallel planes with the contacting face of one finger substantiallycoplanar with the contacting face of the other. These two paralleloffset fingers are adapted to engage the like fingers of another contactin interleaving relation so that the substantially coplanar contactingfaces and the inner edges of the fingers of one contact engage thesubstantially coplanar contacting faces and inner edges of the fingersof the other contact. Preferably the offset fingers overlap slightly,either edgewise or flatwise, so that the slight deformation required inhermaphroditic engagement provides a positive contacting pressure.Preferably, also, an enlarged aperture is provided at the base of thefingers to relieve stresses at the end of the dividing slit. Tofacilitate longitudinal sliding engagement of two like contacts, theouter or leading tips of the fingers of each contact are inclinedoutwardly (i.e. away from the medium plane) in opposite directions.

M-y invention will be more fully understood and its various objects andadvantages further appreciated by referring now to the followingdetailed specification taken in conjunction with the accompanyingdrawing in which:

FIG. 1 shows at A a fragmentary perspective representation of a singlecontact embodying my invention, and at B a fragmentary perspectiverepresentation of a pair of such contacts in fully mated contactingengagement;

FIG. 2 presents three fragmentary views of a pair of such contacts inmated engagement, these views showing the mating heads in side elevation(A) in plan view (B) and in longitudinal cross section (C) taken on theline CC of FIG. 213;

FIG. 3 presents transverse cross-sectional views of a single contacthead (A) and a pair of mated contact heads (B) to illustrate therotational forces involved;

FIG. 4 presents five transverse cross-sectional views of mating heads toillustrate several embodiments of the invention designed to overcomerotational forces;

FIG. 5 is a transverse cross-sectional view of a multiplanar contactembodying my invention and shown mated with a bifurcated uniplanarcontact of the prior art;

FIG. 6 is a fragmentary view in top plan of a contact showing inparticular the formation of an undesired part by inaccurate slitting ofthe contact head; and

FIG. 7 is a view similar to FIG. 6 showing an embodiment of theinvention which eliminates the adverse effects of the undesired part inFIG. 6.

Referring now to the drawing and particularly to FIG. 1, I have shown atFIG. 1A a single electric connector contact embodying my invention. Thecontact is formed from a blade or flat strip of electric conductingmaterial to provide at one end a base or mounting portion 10 and at theopposite end a multiplanar mating head or contacting portion 11. Whileit will be understood that the base or mounting portion 10 may be formedin a variety of ways to provide suitable affixation to a support of anydesired nature, I have shown by way of illustration a mounting enddesigned primarily for connection to a printed circuit board. For thispurpose a side portion 12 of the base is turned downwardly at an angleof approximately 45 to the planes of thecontact fingers and is providedwith a pair of spaced-apart mounting posts 13 adapted for insertionthrough suitable apertures in a printed circuit board (not shown). Thereason for the 45 angle of the side portion 12 will be explainedhereinafter.

The mating contact head portion 11 of my improved contact is slitlongitudinally to define a single pair of contact fingers 14 and 15 ofsubstantially equal length and disposed in closely spaced paralleledge-to-edge relation, the inner end of the slit terminating in anenlarged stressrelieving aperture 16 at the base of the fingers. Theplanar faces of the fingers 14 and 15 are of appreciably larger areathan the edge surfaces, and by the means described below one flat faceof each finger is arranged to provide broad surface contact area withfiat faces of identically configured fingers of another contact. The twofinger faces of each contact which engage finger faces of anothercontact are opposite to each other and will be referred to hereinafteras contacting faces.

The contact fingers 14 and 15 are relatively offset in a directionperpendicular to the planes of their faces and by an amount equalapproximately to the thickness of the fingers. While it will be evidentto those skilled in the art that this offset may be accomplished in avariety of ways, I have shown by way of illustration an upset ordeformation of a base portion of the contact finger 14. In theillustrated embodiment of the invention the base portion of finger 14 isshown divided from the supporting base portion 10 by a lateral notch 17,and offset of the finger 14 is effected by a longitudinal bend 18 in thestrip between the aperture 16 and the notch 17. It will, of course, beevident to those skilled in the art that the fingers may be offset intoparallel planes by bending one or the other or both of the fingerstransversely in the region of their base. It will be apparent thatoffsetting of the fingers 14 and 15 in the amount described results inbringing the lower contacting face of the finger 14 into substantiallycoplanar relation with the upper contacting face of the finger 15 in themanner generally illustrated in all the cross-sectional views of FIGS.2, 3, 4 and 5. In order to facilitate mating of the contact head 11 bylongitudinal sliding engagement with another contact head of identicalconfiguration, the forward or leading edges of both contact fingers 14and 15 are inclined or bent outwardly (i.e. away from the median planeof the blade) in opposite directions, as at 19 and 20 respectively. Theoutturned leading tips 19 and 20 are preferably rounded on their outersides as shown and formed with flat, outwardly inclined, adjacent innersides as at 19a and 20a.

At FIG. 18 I have illustrated in perspective view a pair of electriccontacts of the configuration described above disposed with their matingcontact fingers in full interleaved engagement. In FIG. 1B a firstcontact having a base portion 10 and a pair of contact fingers 14 and 15is shown with the contact head in fully mated engagement with a secondcontact having a base portion 10a and a pair of contact fingers 14a and15a. It will be observed that in this engaged position the offsetfingers 14 and 15 are interleaved in complemental relation with theoffset fingers 14a and 15a so that the substantially coplanar contactingfaces and the inner edges of the fingers of one contact engage thesubstantially coplanar contacting faces and inner edges of the fingersof the other contact. Specifically, the lower contacting face of finger1401, the upper contacting face of finger 15a and the inner edges ofthese fingers engage respectively the upper contacting face of finger15, the lower contacting face of finger 14 and the inner edges of thelatter fingers.

In the engaged position of a pair of my improved hermaphrodite contactsas illustrated at FIG. 1B, the

position of full mating engagement is defined and limited by engagementof the outturned leading tip of one contact finger on each contact withthe rear wall of the base aperture 16 of the other contact. Theinterleaved relationship of a pair of the contacts as shown at FIG. 1Bis further illustrated in plan and elevation at FIGS. 2A and 2B. Thecross-sectional view of FIG. 2C is taken along the line C-C of FIG. 2B.In all the views of FIG. 2 the same reference numerals utilized at FIG.1B are used to identify the like parts. Inspection of my improvedcontact reveals that it can successfully mate with another contact whenin either of two positions spaced angularly about its longitudinal axisby Thus, rotation of the contact shown in FIG. 1A about its longitudinalaxis from its illustrated position to a position spaced angularlytherefrom by 180 serves to merely reverse the relative positions of thetwo contacting faces which are of the two contacting faces which arestill effective as such in their new positions.

Having now described the overall configuration of each multiplanartwo-finger contact and the interleaving relation of a pair of suchcontacts, it is desirable to consider more particularly the availablemeans for providing contact pressure at the mating surfaces andcounterbalancing rotational forces resulting from such contact pressure.It will be evident that if the substantially coplanar contacting facesof each connected pair of contact fingers were in exact coplanarrelationship, the engage ment of a pair of such contacts would producelittle or no contact pressure. Accordingly, it is desirable that someslight overlap of each connected pair of fingers be provided, asillustrated for example at FIG. 3A. In that figure the fingers 14 and 15are shown slightly overlapped edgewise so that the lower contacting faceof finger 14 is slightly offset, and thus only approximately coplanar,with respect to the upper contacting face of the finger 15.

To illustrate the rotational forces involved in engaging two suchcontacts each having its fingers in slightly edgewise overlappedrelation, I have illustrated at FIG. 3A a slight lateral separationbetween the fingers 14 and 15. If now a similar pair of overlappedfingers 14a and 15a are interleaved with the fingers 14 and 15, eachconnected pair of fingers tends to force the cooperating pair of fingerstoward an exactly coplanar relationship of their contacting faces; thatis the fingers exert upon eachother bending forces in directionsperpendicular to their contacting faces. These bending forces tend torotate the overlying fingers away from each other as shown at FIG. 3B,and such rotation is limited only by edge engagement of the fingers andtheir relative rigidity against spreading. It is evident of course thatin an engagement such as shown at FIG. 3B the contact fingers could bebrought back into parallel planar relationship by force exterted upontheir mounting ends. This, however, would require very rigid mountingsfor each contact and would eliminate the slight looseness or float whichis preferably provided in the mounting of each contact of a large array.Accordingly, therefore, I have provided means for counterbalancingwithin the contact head itself the rotational forces illustrated at FIG.3B. Several arrangements for effecting such counterbalance areillustrated at FIG. 4.

At FIG. 4A I have shown in cross section an offset pair of parallelcontact fingers 14 and 15 constituting the mating head of a singlecontact with the fingers slightly overlapped in an edgewise direction toprovide c0ntact pressure against the mating fingers of another contact.In order to counterbalance the rotational forces generated byinterleaving of two pairs of such overlapped fingers, I form theadjacent inner edges of each connected pair of fingers with a slightinward chamfer toward the median plane of the contact. In the embodimentshown at FIG. 4A this chamfer is produced by breaking away the edge ofeach finger on the side toward its contacting face as is done almostunavoidably in any common stamping operation. This produces at the outerside of the inner edge of each finger an inwardly protruding lip 21, thelips 21 extending in opposite directions. It will now be evident from anexamination of FIG. 4B that when tw contacts having the cross-sectionalconfiguration of FIG- 4A are interleaved, the lips 21 of the upperfingers are brought into engagement and the lips 21 of the lower fingersare similarly brought into engagement. This edgewise engagement producesin each connected pair of contact fingers a lateral spreading force in adirection parallel to the contacting faces. Since the fingers arerelatively rigid in this direction, these spreading forces effectivelyovercome the rotational forces generated by contact pressure flexure ofthe fingers perpendicular to their contact faces.

At FIG. 40 I have illustrated in cross-sectional view another method ofproducing oppositely directed chamfers at the adjacent inner edges of apair of connected contact fingers. As illustrated at FIG. 4C, the outerplanar surface of each finger has coined therein a longitudinal groove25 parallel to the dividing slit. By this means the outer portion ofeach inner edge is deformed toward the other finger.

I have found that while it is desirable to ensure firm edge engagementof interleaved contacts by opposite chamfering of the inner edges of thefingers as described in connection with FIGS. 4A, 4B and 4C, adequateedge engagement and force counterbalance may be provided by other means.In FIG. 4D, for example, I have shown a cross-sectional view of theoffset fingers of a single contact with the fingers slightly overlappedin an edgewise direction and in such close proximity that the rotationalefiect illustrated at FIG. 3B is not appreciable or sig nificant. Itwill be understood of course that since the counterbalancing forces setup by edge engagement depend upon the rigidity of the fingers againstlateral spreading, the effectiveness of any arrangement wherein edgeengagement is provided to counterbalance flatwise contact pressure isenhanced by utilizing fingers having a large width dimension relative totheir thickness.

At FIG. 4B I have illustrated another embodiment of my invention whereinthe offset contact fingers 14 and of a single contact (shown in crosssection) are slightly overlapped along the common plane of their facesor flat wise. By this arrangement, edgewise contact pressure is providedagainst a cooperating pair of interleaved fingers by lateral spreadingdeformation of each pair. While of course rotational forces aregenerated by such deformation, these forces are counterbalanced byfiatwise contact engagement. This counterbalance can be made optimallyeffective if the opposite contacting faces of the connected fingers aremaintained as nearly as possible in precisely coplanar relation asillustrated at FIG. 4E.

To illustrate that my improved two-finger multiplanar contact is adaptednot only for hermaphroditic self-mating interconnection with a contacthaving an identically con figured mating head but is adapted also forcooperation with bifurcated uniplanar contact having a differentlyconfigured mating head, I have shown such an interconnection in crosssection at FIG. 5. In this figure the offset fingers 14 and 15constitute the mating head of a contact embodying my invention suchas'shown at FIG. 1. Since the inner parallel edges of the fingers 14 and15 are in approximately coplanar relation as previously described thesefingers provide adjacent these edges two pairs of perpendicularlydisposed surfaces, constituted in each case by a contacting face of onefinger and an inner edge surface of the other. Thus, in FIG. 5 I haveshown in engagement with these two pairs of surfaces the two coplanarcontact fingers 22 and 23 of a bifurcated uniplanar contact havingrounded or tapered adjacent inner edges. Such a bifurcated uniplanarcontact is illustrated in Re. Patent 23,547 issued to Benjamin Fox. Asillustrated in the Fox patent, the bifurcated contact having the fingers22, 23 of FIG. 5 is designed primarily for hermaphroditicinterconnection, but it is evident that it will cooperate equallyeffectively with my improved multiplanar contact. It is observed thatwhen my contact is mated with the uniplanar contact of the Fox patent,the uniplanar contact forms a 45 angle with the planes of the fingers ofmy contact. It is thus seen that when my contact is mounted by the sideportion 12, the fingers thereof form a 45 angle relative to a horizontalplane and thereby mate with a uniplanar contact of the Fox patent whichis located in such a horizontal plane.

It is noted with reference to FIG. 1A that the outturned guide tips 19and 20 are formed by bending the ends of the fingers along parallellines perpendicular to the slit between the two fingers. While thisarrangement is satisfactory, it can under certain circumstances producein the mating heads of contacts so formed parts which interfere withproper mating of two contacts. For example, in FIG. 6 is shown afragmentary view of a contact having the fingers 14 and 15 with theguide tips 19 and 20 formed by bending the ends of the fingers alongparallel lines 30 and 31 which are perpendicular to the slit between thefingers. Ideally, the slit is formed so as to intersect the line ofjointure of the inner edges of'the guide tips. The ideal slit isrepresented by the dash line 32 in FIG. 6. If for some reason, such asinaccuracies in tooling, the slit is not formed ideally but is formedinstead along the line 33 in FIG. 6, a projection 34 is created on oneof the fingers depending upon the direction of lateral shift of the slitfrom the line 32 of ideal slitting. In FIG. 6, it is assumed that theslit is formed along the line 33 to the left of the line of idealslitting so as to form a projection 34 on the finger 14. Subsequentbending of the end of finger 14 about the line 30 will not appreciablydisplace the projection 34 out of the median plane of the finger 14. Itis thus possible that mating of two contacts each containing aprojection corresponding to projection 34 can be prevented by engagementof the two projections during an attempt at mating.

In accord with the invention, I form the guide tips at the ends of thefingers in a manner so that any projection formed on a finger byinaccurate formation of the slit between fingers is displaced out of theplane of the associated finger. I accomplish this desirable result bybending the ends of the fingers about oblique lines which causesmovement of the undesired projection out of the plane of the associatedfinger. In FIG. 7, there is shown part of a contact including fingers 14and 15 formed by the slit 33 which is displaced to the left from theline of ideal slitting to provide the undesired projection 34. Toeliminate the adverse effect resulting from formation of the projection34, the ends of the fingers 14 and 15 are bent about oblique lines 35and 36 to form the guide tips 37 and 38 which perform the same functionas the tips 19 and 20 previously described. The lines 35 and 36 extendfrom the outer edges of the fingers toward the inner end of the slit 33to the inner edges of the fingers so that bending of the end of finger14 about the line 35 results in movement of the projection 34 out of theplane of finger 14 where it cannot engage a corresponding projection onanother contact during contact mating.

While I have described a preferred embodiment of my invention by way ofillustration, many modifications will occur to those skillled in theart. I therefore wish to have it understood I intend in the appendedclaims to cover all such modifications as fall within the true spiritand scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A detachable electric connector contact comprising a blade ofresilient electrically conducting material having a base portion at oneend and a longitudinally split multiplanar mating head at the oppositeend, the split in said mating head having an enlarged aperture at itsinner end and defining a single pair of flat fingers disposed in closelyspaced edge-to-edge parallel relation, each of said fingers having aplanar contacting face with the contacting faces parallel and oppositelypositioned on the fingers, said fingers being relatively offsetperpendicular to their contacting faces with their contacting facessubstantially coplanar, the leading tips of said fingers being outturnedaway from each other and out of the planes of the respective fingers tofacilitate complemental mating with a contact having a like mating headby longitudinal sliding engagement, said tips being outturned aboutoblique lines extending from the outer edges of said fingers towards theend of said split to the inner edges of said fingers.

2. A detachable electric connector contact comprising a blade ofresilient electrically conducting material having a base portion at oneend and a longitudinally split multiplanar mating head at the oppositeend, the split in said mating head having an enlarged aperture at itsinner end and defining a single pair of fiat fingers disposed in-closelyspaced edge-to-edge parallel relation, each of said fingers having aplanar contacting face with the contacting faces parallel and oppositelypositioned on the fingers, said fingers being relatively offsetperpendicular to their contacting faces with their contacting facessubstantially coplanar, the leading tips of said fingers being outturnedaway from each other and out of the planes of the respective fingers tofacilitate complemental mating with a contact having a like mating headby longitudinal sliding engagement, said tips being outturned aboutoblique lines extending from the outer edges of said fingers towards theend of said split to the inner edges of said fingers, said fingers beingin slightly overlapped relation.

3. A detachable electric connector contact comprising a blade ofresilient electrically conducting material having a base portion at oneend and a longitudinally split multiplanar mating head at the oppositeend, the split in said mating head defining a single pair of fiatfingers disposed in closely spaced edge-to-edge parallel relation, eachof said fingers having a planar contacting face with the contactingfaces parallel and oppositely positioned on the fingers, said fingersbeing relatively offset perpendicular to their contacting faces withtheir contacting faces substantially coplanar, the leading tips of saidfingers being outturned away from each other and out of the planes ofthe respective fingers to facilitate complemental mating with a contacthaving a like mating head by longitudinal sliding engagement, said tipsbeing outturned about oblique lines extending from the outer edges ofsaid fingers towards the end of said split to the inner edges of saidfingers, said fingers being in slightly overlapped relation.

References Cited UNITED STATES PATENTS 2,125,816 8/1938 Reynolds 339-472,713,154 7/1955 Bilsborough 339-47 2,996,026 8/1961 Batcheller 339-2563,011,143 11/1961 Dean 339-49 3,065,441 11/ 1962 Leonard 339-493,115,379 12/1963 McKee 339-47 3,149,894 9/1964 Fox 339-49 X FOREIGNPATENTS 218,200 4/ 1942 Switzerland.

MARVIN A. CHAMPION, Primary Examiner. PATRICK A. CLIFFORD, AssistantExaminer.

1. A DETACHABLE ELECTRIC CONNECTOR CONTACT COMPRISING A BLADE OFRESILIENT ELECTRICALLY CONDUCTING MATERIAL HAVING A BASE PORTION AT ONEEND AND A LONGITUDINALLY SPLIT MULTIPLANAR MATING HEAD AT THE OPPOSITEEND, THE SPLIT IN SAID MATING HEAD HAVING AN ENLARGED APERTURE AT ITSINNER END AND DEFINING A SINGLE PAIR OF FLAT FINGERS DISPOSED IN CLOSELYSPACED EDGE-TO-EDGE PARALLEL RELATION, EACH OF SAID FINGERS HAVING APLANAR CONTACTING FACE WITH THE CONTACTING FACES PARALLEL AND OPPOSITELYPOSITIONED ON THE FINGERS, SAID FINGERS BEING RELATIVELY OFFSETPERPENDICULAR TO THEIR CONTACTING FACES WITH THEIR CONTACTING FACESSUBSTANTIALLY COPLANAR, THE LEADING TIPS OF SAID FINGERS BEING OUTTURNEDAWAY FROM EACH OTHER AND OUT OF THE PLANES OF THE RESPECTIVE FINGERS TOFACILITATE COMPLEMENTAL MATING WITH A CONTACT HAVING A LIKE MATING HEADBY LONGITUDINAL